var start =0;
var sum =0;
while (start<=100) {
    start+=1;
    if (start%2==0) {
        sum+=start;
    }
    if (sum>=1000) {
        break;
    }
}
console.log(start);

while (start<=100) {
    start+=1;
    if (start%2==0&&start%7==0) {
        sum+=start;
    }
}
console.log(sum);

var year =199;
while (year<=2022) {
    year+=1;
    if (year%4==0&&year%100!=0) {
        console.log(year);
    }
}

var i = prompt('请输入成绩')
if (i>=90&&i<=100) {
    alert('A')
}else if (i>=80&&i<90) {
    alert('B')
}else if (i>=60&&i<80) {
    alert('C')
}else if (i>=0&&i<=60) {
    alert('D')
}else{
    alert('不合法')
}